Reflection-type projection screen

ABSTRACT

A reflection type projection screen comprising an aluminum support, the surface of which has rolling stripes thereon. The surface of the support further having a light-reflecting property such that light impinging upon the surface of the support will be reflected in a direction such that the amount of light reflected in a direction perpendicular to the rolling stripes is 1.5 to 3.0 times that reflected in a direction parallel to the rolling stripes. The support further having coated thereon a light scattering layer comprising silica powder dispersed in a hydrophobic polymer, and method for preparing same.

United States Patent [191 Fujisaki et al.

15 REFLECTION-TYPE PROJECTION SCREEN [75] Inventors: Hiroshi Fujisaki;Shizuo Miyano; Asaji Kondo, all of Asaka-shi,

Saitama, Japan i [73] Assignee: Fuji Photo Film Co., Ltd., MinamiAshigara-shi, Kanagawa, Japan [22] 7 Filed: Oct. 2 9, 1970 [21] Appl.No.: 85,068

[30] Foreign Application Priority Data Oct. 29, 1969 Japan ..44/86581[52] US. Cl. ..350/126, 350/127, 350/127 [51] Int. Cl. ..G03b 21/60 [58]Field of Search ..350/127, 123, 125,

[451 Apr. 10, 1973 9/1941 Stableford .350/ 129 4/1967 Morgan ..350/ l 29[57] ABSTRACT A reflection type projection screen comprising an aluminumsupport, the surface of which has rolling stripes thereon. The surfaceof the support further having a light-reflecting property such thatlight impinging upon the surface of the support will be reflected in adirection such that the amount of light reflected in a directionperpendicular to the rolling stripes is 1.5 to 3.0 times that reflectedin a direction parallel to the rolling stripes. The support furtherhaving coated thereon a light scattering layer comprising silica powderdispersed in a hydrophobic polymer, and method for preparing same.

12 Claims, 3 Drawing Figures PAIENILUAPRI H I 3.726.583

FIG. I L

02 o i p2 new M INVENTORS HIROSHI FUJISAKI SHIZUO MiYANO ASAJI KONDO BY4m 2M M ZA'M J Mc/ZQQK ATTORNEYS REFLECTION-TYPE PROJECTION SCREENBACKGROUND OF THE INVENTION The present invention relates to areflection-type projection screen wherein a light-scattering layercomposed of silica powder dispersed in a hydrophobic polymer is formedon an aluminum support, having thereon, fine rolling strips in adefinite direction. In this manner, the projected images on the screencan be observed as images having sufficient brightness. This holds trueeven in a light room and as another feature, the reflected light isprovided with directionally as well.

For observing the reflected image of a cine film or a transparentpositive film, a system is employed in which the image of the film isprojected onto a screen and the reflected image is observed. It isnormal to observe these reflected images on a screen in a dark roomsince the faculty of the screen is insufficient. That is to say, since aconventional screen is mainly composed of paper, cloth or an opaquematted base, such as resin layer containing white pigment, the projectedlight is scattered away in all directions and fails to come into theview of the observer. Therefore, the brightness of the image projectedonto the screen is low. On the other hand, if such a screen is used in alight room, the contrast of the image is lowered by light uniformlyprovided onto the screen. Consequently, it is necessary, althoughundesirable, to darken the room for increasing the contrast of image. Ifhowever, it would be possible to practice projection in a light room, itwould provide highly profitable.

It is therefore the primary object of the present invention to provide aprojection screen which can function excellently in a light room and yetnot inhibit the view to the audience.

SUMMARY OF THE INVENTION The inventors have conducted many experimentsbased on the idea that, if the surface has the ability to reflect thegreater part of the projected light as well as scatter effectively, thereflected light, a reflection typeprojection screen can be provided,which produces a bright observable image.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be furtherexplained by referring to the accompanying drawings, in which;

FIG. 1 is a cross-sectional view showing an embodiment of thereflection-type projection screen of this invention and,

FIG. 2 (A) is a flat view and FIG. 2 (B) is a cross-sectional viewshowing an aluminum support used for the reflection-type projectionscreen.

The reflection-type projection screen of this invention has theelementary structure as shown in FIG. 1. A hydrophobic polymer layer 4,having dispersed therein fine silica powder 3, is formed as a lightscattering layer 5, on an aluminum support 2, having on the wholesurface thereof fine rolling stripes or light reflecting uneven stripesl in a definite direction.

FIG. 2 (A) and FIG. 2 (B) illustrate the aluminum support 2 havingrolling stripes 1 on the surface, which is used in the instantinvention. When an aluminum plate or an aluminum foil is produced byrolling, cracks 6 are formed with distances of about 0.5 to aboutmicrons by the rolling pressure. The direction of the cracks areperpendicular to the axial direction of the roll but the lengths and thedepths of'the cracks are ir regular. FIG. 2(A) is a plane view showingthe pattern of the cracks and FIG. 2 (B) is a cross-sectional view. Asshown in FIG. 2(8), the surface has a very complicated uneven structure.

In the embodiment shown in FIG. 1, the light projected on the surface ofthe screen, perpendicularly from the direction L, is reflected at thestrips on the aluminum surface in a direction perpendicular to thestrips. Thus, there is less reflection in a direction parallel to thestripes. The light reflected at the stripes is further scattered by thesilica powder dispersed in the light scattering layer to expand thedirection. When light is projected effectively onto the projectionscreen of the present invention, a greater part of the light isreflected, thus contributing to the brightness of the screen. Thereflected light has such directionality that the amount of the lightreflected in the perpendicular direction of the rolling stripe is 1.5-3times that reflected in the parallel direction to the stripe. Moreover,if the brightness of a standard aluminum oxide-type scattering plate isassumed to be one, the brightness of the projection screen of thisinvention ranges from 10 to 20.

The materials applicable to the present invention will be described asfollows:

DETAILED DESCRIPTION OF THE INVENTION The aluminum support contemplatedis an aluminum foil or an aluminum plate rolled by a roll andpreferably, an aluminum plate or foil which has from 200 to 2,000rolling stripes per one cm. on the surface thereof. Moreover, if thesurface is stained, the reflectivity of light is reduced and hence afresh and stainless material is preferable as the aluminum support. Thesize of the silica powder is preferably less than 10 microns and it ishighly desirable to use a suitable mixture of silica powders having thesizes of from 5 millimicrons to 5 microns. Illustrative of these areSiloid (made by Fuji Devillin Chemical Co.), Aerosyl (Degus- -sa A. G.),and Carbosyl (made by Cabott Co.

It is preferable that the hydrophobic polymer used in the presentinvention have good adhesivity to aluminum and very little color.Illustrative of these are resins having good solvent solubility, such asan unsaturated polyester resin, an alkyd resin, varnish, a vinylicresin, and an acrylic acid resin.

The amount of the silica powder may range from 1/20 to 2 times by weightof the polymer employed, and preferably, one-tenth to one-half by weightof the polymer.

The present invention relates to the improvements of the inventions ofU.S Pat. Application Ser. Pat. No. 854,174 now U.S. Pat. No. 3,587,735and 855,185, now abandoned. Since the polymers employed in the lightscattering layer of the instant invention are hydrophobic in nature,water resistance and weather resistance of the projection screen isimproved as compared, with those screens employing hydrophilic polymersas disclosed in the above mentioned applications. Furthermore, in theinstant. invention, the hydrophobic polymer contributes to protectingthe surface of the aluminum support. The strength of the projectionscreen is greatly increased and the surface of the screen maybe washedor wiped by cloth. When an aluminum support having a thickness of from0.1 0.5 mm. is employed, the flatness of the screen is good and thescreen iseasily handled.

Preferably, the thickness of the light scattering layer should rangefrom 5-l00n. Excellent results have been obtained with p. and 30p 7 Abetter understanding of the present invention will be obtained from thefollowing examples which are merely illustrative and not limitative ofthe present invention. All parts are by weight unless otherwise stated.

EXAMPLE 1 An aluminum plate (made by Sumitomo Kinzoku K. K.) of 0.3 mm.in thickness 1 m. in width, and 0.8 m, in length and having distances of5-20 microns between each rolling stripe was used as the support. Fiveparts of an aluminum-painting resin, 'Ester Resin (trade name, made byToyoBo KK.) was dissolved in a mixed solvent of 15 parts(by volume) ofmethyl ethyl ketone ketone, 6 parts (by volume) of cellosolve acetate, 9parts (by volume) of toluene, and 15 parts (by volume) of xylene. Then,1 part of Carbosyl was dispersed in the solution by means of anultrasonic emulsifying machine. The resultant dispersion was employed asthe material for the light scattering layer.

By applying the dispersion to the aluminum support in a thickness of 15microns and drying it, the projection screen of the present inventionwas obtained. When the projection screen was disposed so that thedirection of therolling stripes were perpendicular and a picture wasprojected on the screen, the brightness of the screen was 15 when thebrightness of the standard scattering plate was taken as one. Also, theangle 0.5) at which the brightness of the light projectedperpendicularly to the screen, was l5.5 in the width direction and 52 inthe length direction.

EXAMPLE 2.

An aluminumplate (made by Alcoa Co.) of 0.2 mm. in thickness, 50 cm. inwidth, and 40 cm. in length and having the distance of 5-30 micronsbetween each rolling stripe was used as the aluminum support. 20

. parts of Ester Resin -20 was dissolved in a solvent mixture of 30parts (by volume) of methyl ethyl ketone, 20

parts (by volume) of toluene, and 25 parts (by volume) of xylene. Then,1 part of Carbosyl (silica powder having a size of an order ofmillimicrons) and 0.5 parts of Silonid (silica powder having a size ofan order of millimicrons) were dispersed in the solution. Thedispersionthus obtained was used as the material for the lightscattering layer for the projection screen.

By applying uniformly the dispersion to the aluminum support in athickness of 30 microns, the projection screen of the present'inventionwas obtained.

Although the present invention has been adequately 2 described in theforegoing specification and examples included therein, it is readily aparent that various changes and modifications may e made withoutdeparting from the scope thereof.

What is claimed is:

1. A reflecting type projection screen comprising a light reflectingaluminum support, the surface of which has rolling stripes impartedthereon by passing said aluminum support between rollers; the surface ofsaid aluminum support further having a light reflecting property suchthat light impinging thereon is reflected therefrom in suchdirectionality that the amount of light reflected in a directionperpendicular to the rolling stripes is 1.5 to 3.0 times that reflectedin a direction parallel to the rolling strips; said aluminum supporthaving coated thereon a light scatting layer comprising silica powderdispersed in a hydrophobic polymer.

2. The projection screen of claim '1, wherein said hydrophobic polymeris a member selected from the group consisting of an unsaturatedpolyester resin, an alkyd resin, 21 varnish, a vinylic resin and anacrylic resin.

3. The projection screen of claim 1, wherein the particle size of saidsilica powder is less than 10 4. The projector screen of claim 3,wherein the particle size of said silica powder ranges from 5 mp to5,1,.

5. The projection screen of claim I, wherein the times by weight of thehydrophobic polymer.

6. The projector screen. of claim 5, wherein the amount of said silicapowder ranges from one -tenth to one-half times by weight of thehydrophobic polymer.

7. The projection screen of claim 1, wherein the thickness of said lightscattering layer ranges from 5 to 100 p.

8. The projection screen claim 1, wherein the thickness of the aluminumsupport ranges from 0.1 to

9. The projection screen of claim 1, wherein the amount of rollingstripes present ranges from 200 to 2,000 1 cm. on the surface.

10. The projection screen of claim 7, wherein th thickness of the lightscattering layer is 15 p..

11. The projection screen of 'claim 7, wherein the thickness of thelight scattering layer is 30 u.

12. The projection screen of claim 1,.wherein'the distance between therolling stripes ranges from 0.5 to 20 p.

2. The projection screen of claim 1, wherein said hydrophobic polymer is a member selected from the group consisting of an unsaturated polyester resin, an alkyd resin, a varnish, a vinylic resin and an acrylic resin.
 3. The projection screen of claim 1, wherein the particle size of said silica powder is less than 10 Mu .
 4. The projector screen of claim 3, wherein the particle size of said silica powder ranges from 5 m Mu to 5 Mu .
 5. The projection screen of claim 1, wherein the amount of said silica powder ranges from 1/20 to 2.0 times by weight of the hydrophobic polymer.
 6. The projector screen of claim 5, wherein the amount of said silica powder ranges from one-tenth to one-half times by weight of the hydrophobic polymer.
 7. The projection screen of claim 1, wherein the thickness of said light scattering layer ranges from 5 to 100 Mu .
 8. The projection screen claim 1, wherein the thickness of the aluminum support ranges from 0.1 to 0.5mm.
 9. The projection screen of claim 1, wherein the amount of rolling stripes present ranges from 200 to 2,000 /1cm. on the surface.
 10. The projection screen of claim 7, wherein the thickness of the light scattering layer is 15 Mu .
 11. The projection screen of claim 7, wherein the thickness of the light scattering layer is 30 Mu .
 12. The projection screen of claim 1, wherein the distance between the rolling stripes ranges from 0.5 to 20 Mu . 